Lawn-mower sharpener.



G. L. KNOWLTON.

LAWN MOWER SHRPENER.

APPLIGATION FILED MAY 1, 1913.

l ,090,075 Patented Mar. 10, 191i4 @uvm/1to1 @www @60H18 LKH ovv/ton yf/1MM fr@ l,

ttoznun EN 1TH@ STATES PATENT @FFlQEo GEORGE L. KNOWLTON, 0F PHILADELPHIA, PENNSYLVANIA.

LAWN-MOWER SHARPENER.

To all whom it may conf/ern Be it known that I, Guiones L. KNowL'roN, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and usetul Improvements in Lawn-Mower Sharpeners: and 1 do declare the following to be a full, clear, and exact description ot' the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to metal implements, and more especially to tools for treating cutting implements; and the 0bject oit' the same :is to produce a hand tool by means ot which the spiral blades of lawn mowers `may be sharpened. This object is accomplished by constructing the tool in the manner hereinaftermore fully described and claimed, and as shown in the drawings wherein- Figure 1 is an elevation ot' what might be called the front side ot this tool; Fig. 2 is a lower edge view thereof; Fig. 3 is a hori- Zontal section on the line 3 3 ot Fig. 1; Fig. 4- is an end view; and Fig. 5 is a vertical section on the line 5 5 of Fig. 1.

1n the drawings the framework of this tool is shown as composed of two parts or members, one of which `is the front member 1 whose upper edge is curved inward toward the other member as at 2, whose body contains a centrally disposed and inwardly projecting internally threaded boss 3, and whose lower edge has a flat inner face fl and above it a longitudinal shoulder 5. The other or rear member 11 curves inward at its upper edge as at 12, is pierced at its center for the reception of a screw 13 whose threads engage the hole in the boss 3, and near its lower edge has a shoulder 15, beneath the same a flat tace 14, and beneath the latter in turn a downward projection or `guide 1G between whose inner edge and the tace 14; said guide may be shouldered to a slight extent as at 17 so that the face 14 with the two shoulders 15 and 17 present in effect a groove alongr the lower portion of this member 11. The upper end of this member is provided with notches 18 to receive tongues 8 at the upper end of the Specification of Letters Patent.

Application led May 1, 1913.

Patented War. 10, 1914.

Serial No. 764,833.

member l when the two membersl are brought together by tightening up on the screw and these iuterengaging tongues and notches hold the members in proper relative position. Between their :faces 4t and 11tis disposed a File Q0 which is preferably square in cross section as seen in Fig. 5 and et a length equating that ot the two members as seen in Fig. Attention is directed to the fact that the tacos il and 1t are disposed slightly oblique to a vertical plane through the entire tool, as seen in Fig. 4l. with the result that the lowermost or working tace ot the tile 20 stands at a slightly acute angle to the 'tace ot the guide 1G.

An imporaut itcature oi the present invention consists in the provision ot means for overcoming excessive -friction when this tool is used on a lawn mower blade B, as well as means ttor adapting the tool to the curvature which results -trom the spiral or helical formation ot such blade in the machines now commonly used. While the 'face of the guide 16 is straight throughout its length, it is interrupted at its center bv a notch or cutaway portion 21, and within this cutaway stands a roller 22 mounted on a screw or other pivot 25) which passes upward through it and into the lower edge ot the member 11. The disposition ot this pivot is such that the wearing or active 'tare ol" the roller 22 projects slightly beyond the inner tace ot' the guide 1G as seen in Figs. 2 and Zt, with the result that when the tool is employed on a lawn mower blade having the usual curvature. it it touches the guide 16 at the extremities Q4 ot the latter, the roller 22 will touch said blade between such extremities providing the length of the guide 16 is sutlicient. The result is that the blade is firmly held by the three points o'l" Contact which the tool makes with its rear side. On the opposite side the drawing inward ot the lower edge o't the member 1 which is et'- fected by tightening up the screw 13 ca uses the face 4t to abut against one ot the side faces of the tile 2O so that the shoulders 5 and 15 pass above its upper if'ace as seen in Fig. 4, with tht` result that the lower flat face of the square file will be held at a slightly acute angle to the tlat inner 'face ot the guide 1G so as to the proper bevel eil to the cutting edge of the blade B. For holding the blade in this position while the tool is reciprocated along its edge, I provide a leaf spring 25 secured at| its upper end to the member 1 by a screw 26 or otherwise, passing along over the front face of the same and normally springing away from it to a slight extent as seen in Figs. 4 and 5, possessing at about its midlength a slot 2G through which passes a set screw 27, and inturned at its lower end at 28 where it carries a rivet or other pivot 29 for a second roller 30 standing opposite the first roller 22. The inner end of the screw 27 takes into a threaded opening in the front member 1, and it is obvious that by setting up this screw the shoulder 27 thereon bears against the lea-f spring 25 and throws the inner end of the latter and its roller inward toward the other roller 22, or toward the guide 16 if this roller 22 is not employed, as I contemplate omitting it where the knife blade is straight.

It is well known to those who have used tools of this kind that it is extremely diicult to reciprocate the le or other abrading instrument along the length of a blade B which is spiral or helical, and at the same time hold it accurately in such relative position thereto that it will sharpen the blade on a proper bevel and will maintain that bevel throughout the length of its stroke. The present tool will permit the operator to accomplish this end nicely. rlhe spring pressure of the roller 30, brought about by the spring 25 as adjusted by the set screw 27, throws the blade B against the guide 16 and its roller 22, and if the blade'be thicker or thinner than as shown the set screw 27 may be correspondingly adjusted. The height of the face 16 will be sufficient to maintain the entire tool in substantially the plane of the knife blade B, and the inclination of the faces 4 and 14 and therefore the disposition of the lower face of the file 2O will be such that, as it is moved to and fro while the tool is reciprocated, its lower or cutting face maintains constantly the proper angle with respect to the blade to form a bevel thereon as desired. The parts are by preference entirely of metal, suitably treated to prevent rust, and the details of the file are unimportant as I prefer to purchase this element from a concern which makes a specialty of its manufacture. It may be that intermediate portions of the two faces 4 and 14 are cut away as seen at 35 in Fig. 2 so as to leave only two lips 36 on each face which come in contact with the file at the ends of the latter, because I find by experience that these liles are not always perfectly straightespecially where they have been highly tempered. The size and shape of parts are immaterial to the successful operation of the invention.

lll/That is claimed as new is:

1. In a tool of the class described, the combination with a front member bent inward along its upper edge and there provided with tongues and having a face along its lower edge with a shoulder above said face and a hollow internally threaded boss about mid-way between said edges; of a rear member bent inward along its upper edge and notched to receive said to-ngues, this member also having a face along its lower edge with a shoulder above said face and a longitudinal guide disposed beneath said face, and an aperture about mid-way between its upper and lower edges, and a screw passing through said aperture and engaging said boss.

2. In a tool of the class described, the combination with a fro-nt member bent inward along its upper edge and having a face along its lower edge which is cut away between its extremities, a rear member similarly constructed, and a rectangular file disposed between said faces; of interlocking elements on the meeting upper edges of said members, and means between these edgesand said faces for drawing the members together, for the purpose set forth.

3. In a tool of the class described, the combination with front and rear members abutting at their upper edges and having toolembracing faces along their lower edges, and means between said edges for drawing said members together; of a longitudinal guide extending along the lower edge of one member beneath its face, a roller opposite said guide, a spring attached to the other member and carrying this roller, and means for adjusting the tension of the spring and the position of the roller.

4. In a tool of the class described, the combination with front and rear members abutting at their upper edges and having toolembracing faces along their lower edges, and means between said edges for drawing said members together; of a longitudinal guide extending along the lower edge of one member beneath its face and interrupted at its center, a roller mounted on a pin in this member and projecting through said interruption, a second roller opposite the first, a spring secured at its upper end to the other member and having its lower end inturned and its body slotted, a pivot through said inturned end and on which this roller is mounted, and a set screw passing through said slot and into this member, for the purpose set forth.

5. In a tool of the class described, the combination with front and rear members abutting at their upper edges and having toolembracing faces along their lower edges, and means between said edges for drawing said members together; of a longitudinal guide extending along the lower edge of one member, a roller standing opposite the 'face In testimony whereof I have hereunto set of sind gulde, a leaf sprlng 1n whose lowel` my hand 1n presence of two subscrlbmg wltend stud roller 1s plvoted, a screw conneetlnof nesses.

its upper end with the opposite member, anc GEORGE L. KNOVLTON. a set screw passing through its body and entnessem gagng this member, for the purpose set BESSIE S. BECK,

forth. HARRY BECK.

Copies of this patent may be obtained for ve cents each, by addressing the "Commissioner of Patents.

Washington, D. C. 

